Which continuous flow hot water system?

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shreyas

80 posts

Master Geek

# 67950 11-Sep-2010 13:00

Hi all,

Not sure if this is the right forum to post this, but here goes nothing.

We are looking to get a continuous flow hot water system installed at our house (currently have an electric hot water cylinder)
We are a family of five and have 2 bathrooms and a kitchen/laundry, so relying on traditional electric hot water cylinder is not an option for us anymore since the water runs out very quickly.

According to the PlumbingWorld website, there are three to choose from - Bosch, Rheem and Rinnai.
Does anyone have any experience with a particular brand, good or bad? I'd greatly appreciate anyone's advice since this is going to be a reasonably significant investment and I want to make the right decision going forward.

Thanks.

http://www.plumbingworld.co.nz/Pages/Catalogues.aspx?search=Continuous+Flow+Hot+Water&page=true&cat=1&subcat=3&fpb=false

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270 posts

Ultimate Geek

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# 378771 11-Sep-2010 13:44

We have a five person family living in a 2 bathroom house and went with the Rinnai Infinity XR26. It seems to do the job just fine.
It works on both mains and low pressure water systems and can use either natural gas or LPG.

Michael Skyrme - Instrumentation & Controls

cyril7

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# 378772 11-Sep-2010 13:55

Hi, from my observation working on new house sites every day Rinnai would probably be the most common being bolted in.

Our house has two bathrooms with 4 occupants of which two teens burn through more carbon points with hot water than you could imagine. The main bathroom, kitchen, washhouse is fed from one Rinnai 24 and ensuite (which includes a spar) is fed from another Rinnai 24, most of the reason for whats connected to what has to do with location as well as load.

Regardless having previously owned a house with similar demands but run off two electric cylinders I can say running cost and assured delivery wise gas continuous flow systems are brilliant and undoubtedly the go.

what is of interest is that we have no seperate controllers for temperature in our house, they are just preset and any adjustment is done by cold mixing as would be done in any other system, guess what I am saying is there is no need for controllers if you dont want them.

Cyril

scuwp

3208 posts

Uber Geek

# 378792 11-Sep-2010 15:38

cyril7: Hi, from my observation working on new house sites every day Rinnai would probably be the most common being bolted in.

Our house has two bathrooms with 4 occupants of which two teens burn through more carbon points with hot water than you could imagine. The main bathroom, kitchen, washhouse is fed from one Rinnai 24 and ensuite (which includes a spar) is fed from another Rinnai 24, most of the reason for whats connected to what has to do with location as well as load.

Regardless having previously owned a house with similar demands but run off two electric cylinders I can say running cost and assured delivery wise gas continuous flow systems are brilliant and undoubtedly the go.

what is of interest is that we have no seperate controllers for temperature in our house, they are just preset and any adjustment is done by cold mixing as would be done in any other system, guess what I am saying is there is no need for controllers if you dont want them.

Cyril

The separate controllers don't seem to be used much nowdays. +1 on the Rinnai. Built 3 houses with infinity systems installed.

My only recommendation is NOT to install it near a bedroom or similar, they are a bit noisy when running.

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timbosan

1566 posts

Uber Geek

# 378796 11-Sep-2010 16:09

We recently (3 months ago) did some major renovations to our house, including the kitchen, which had a hot water cylinder, and with two teenage kids it only lasted for 2 1/2 showers (i.e two teenagers and 1/2 a normal person!).

So we made the decision to get continuous gas, and went with a Rinnai, which has been brilliant.

Just a note - we don't have gas to our side of the street, so we have two big bottles fro Rockgas, approx $125 each delivered I think, and they last about a month each or thereabouts.

Handle9

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# 378798 11-Sep-2010 16:22

If you are going to go down the continuous hot water route you need to make sure of a couple of things.

1. Choose a unit at least one size above what you think you need. The flow rates are generally rated at raising the temperature to 40 degrees (not 55 which is typically where the unit is set to).

2. Make sure you have sufficient gas supply to the unit. You need at 20mm feed to the unit. If you don't have a big enough gas main then you'll end up with a unit that starves and runs hot cold hot cold. I'm going through this at the moment at home. It's going to cost $3k to upgrade all the pipework so I'm going to remove the unit and go back to a mains pressure electric cylinder.

Also if you haven't got gas on your street you're going to end up with very expensive hot water. Bottled LPG is generally at least twice the price of reticulated natural gas. Also you need a conversion kit for the hot water heater.

sleepy

274 posts

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# 378800 11-Sep-2010 16:40

We have Rinnai 24 and has been great, only problem is due to long run a lot of water is wasted in the kitchen before the hot appears so next time we may put small electric cylinder in the kitchen

Remember once seeing a valve that circled the cold water back round into system but cant recall the details

We use 1 cylinder every 5 weeks approx 2 adults, 2 kids. though not sure one off them gets much use for hot water

bazzer

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# 378907 12-Sep-2010 01:44

We just got a Rinnai XR26 put in last week. So far, not that stoked with it. Previously we had a mians pressure electric cylinder. We never had any temperature or pressure fluctuations with people using multiple outlets, and our pressure was great.

We've only had it a few days, but the pressure is definitely not as good (I guess this is to do with the amount of water the unit can heat?) but to be fair we had way more pressure than we needed previously. Also, even running a hot tap makes the shower go cold now so that's a bit useless. I'm a bit disappointed really, but we'll give it a chance and then take it up with the gasfitter.

I don't know if this is normal behaviour, but I can't imagine it is. There's only 2 of us living here so I wouldn't have thought we'd stress the XR26 that much. We particularly mentioned that a priority was multiple showers without disruption so if gas can't deliver that for us, I'll be a bit disappointed.

Regs

Cloud Guru
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Snowflake

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# 379373 13-Sep-2010 17:31

i have a rheem and from reading the rinnai comments above, it seems pretty much the same.

as to bazzer's comment about the water pressure, he might find that his plumber/gasfitter installed a water pressure regulator as part of the and configured it to the recommended settings. it may just be a matter of getting under the house and adjusting the inward pressure (as long as your fittings can all handle it! some new taps/mixers are *not* rated for high pressure). Of course, an XR26 is only ever going to handle up to 30 litres per minute.

The recommended flow rate out of a shower head for energy saving is 9 litres per minute or less.

we have a seperate temperature control in the bathroom and find that if you set the bathroom one to an appropriate temp - e.g. 42degC - and run the mixer at full hot then you just get pressure loss due to other taps turning on, rather than temperature fluctuations.

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Linuxluver

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# 379391 13-Sep-2010 18:38

Any non-gas solutions?

I got the teens to have shorter showers so we have enough water....After 10 minutes other people come in and start using the bathroom - done or not.

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Snowflake

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# 379439 13-Sep-2010 20:31

shreyas: Hi all,

We are looking to get a continuous flow hot water system installed at our house (currently have an electric hot water cylinder)
We are a family of five and have 2 bathrooms and a kitchen/laundry, so relying on traditional electric hot water cylinder is not an option for us anymore since the water runs out very quickly.

you could also potentially consider one of the 'fast recovery' hot water systems. they are available in either gas or electric heat pump models. not sure how fast 'fast' is though..

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Antzzz

181 posts

Master Geek

# 379471 13-Sep-2010 22:06

Handle9:

2. Make sure you have sufficient gas supply to the unit. You need at 20mm feed to the unit. If you don't have a big enough gas main then you'll end up with a unit that starves and runs hot cold hot cold. I'm going through this at the moment at home. It's going to cost $3k to upgrade all the pipework so I'm going to remove the unit and go back to a mains pressure electric cylinder.

+1 on this - was thinking about upgrading our ancient gas hot water cylinder with a continuous flow system. But apparently most of the cylinders have a 15mm connection, which is too small for a continuous flow burner, and costs $$s to upgrade. So have shelved that idea for now - doh!

robbyp

1163 posts

Uber Geek

# 379486 13-Sep-2010 23:01

shreyas: Hi all,

Not sure if this is the right forum to post this, but here goes nothing.

We are looking to get a continuous flow hot water system installed at our house (currently have an electric hot water cylinder)
We are a family of five and have 2 bathrooms and a kitchen/laundry, so relying on traditional electric hot water cylinder is not an option for us anymore since the water runs out very quickly.

According to the PlumbingWorld website, there are three to choose from - Bosch, Rheem and Rinnai.
Does anyone have any experience with a particular brand, good or bad? I'd greatly appreciate anyone's advice since this is going to be a reasonably significant investment and I want to make the right decision going forward.

Thanks.

http://www.plumbingworld.co.nz/Pages/Catalogues.aspx?search=Continuous+Flow+Hot+Water&page=true&cat=1&subcat=3&fpb=false

They are all pretty much the same. Rinnai are the most popular. My plumbing friend however has warning me about a few pitfalls with them.
If something goes wrong with them, they are very expensive to repair, and usually they are cheaper to replace, and only a few people know how to repair them. Expect around 10 years or less life from them. I know an old peoples home whose heaters are about 10 years old, and they are all now being replaced, due to age. Hot water cylinders can last 25 years +
They are more expensive to run over a traditional water heater, if it is being used every day and has high usage.

Nety

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# 379558 14-Sep-2010 09:53

Regs:
you could also potentially consider one of the 'fast recovery' hot water systems. they are available in either gas or electric heat pump models. not sure how fast 'fast' is though..

Although it is not continuous flow or fast recovery we have a Rheem Heat pump hot water cylinder. It is something like 240L and have only managed to drain it when all four of use have long long showers. With general use (and no we don't go for the whole 3 minute shower idea) we never have issues with draining the tank. I notice the new model is 300L so should be even less likely to run out.
The advantage of the heat pump hot water cylinders is how cheap they are to run. We installed the hot water cylinder and a heat pump for heating the house at the same time replacing a wood fire. Over the year our power usage worked out the same as previous years so the savings in hot water heating were enough to off set the additional cost of heating and cooling the house with a heat pump.

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thewalkernz

6 posts

Wannabe Geek

# 379568 14-Sep-2010 10:18

Installed a Rinnai four months ago.

At this stage it has proven to be cheaper than the two low pressure cylinders it replaced. pressure is vastly improved, and there is almost no noticeable effect on other outlets either pressure or temperature wise (e.g when the kitchen tap is on full you hardly notice it in the shower).

Note: it is connected to the gas mains.

We used Safegas, partially due to theirs being the second lowest quote of four (the lowest seemed....rough), their ability to manage the entire connection process, and their insanely good quality and safety rating from Target.

Could be worth checking your local Mitre10 (maybe only the Mega stores) for prices and installation too.

jonherries

1086 posts

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# 379576 14-Sep-2010 10:43

Hi,

Few things to add:

We have a Bosch hydropower system running off lpg.

Our supplier is elgas, and the bottles are $108.30 in Wellington which is the cheapest I could find.

We replace our bottles every 52 days on average since sept 2008 - I have a spreadsheet (heats water, cooks food) - we have an outdoor connection to the bbq installed as well (well worth it).

I read some reviews on the hydropower prior to purchasing and there were some interesting complaints. The complaints were similar to those listed above around capacity and time to heat.

The mechanism in the unit itself uses a small turbine to generate electricity to spark the gas this takes flow (time x volume). This means a gas hot water system will push cold until it lights.

The gas comes into its own if you:

a: can't afford to run out of hot water
b: have times where you don't want to heat water (eg. work out of town, holidays etc)

Further advantage to our system is that we don't require mains electric to run it (ie. hot water in a power cut ala chch in the earthquake).

On a side note I have seen a reclamation system which is a heat-exchanger below the shower waste where inflow to the gas/electric cylinder heater is wrapped around the waste below the floor. Presumably if you insulated it well and used copper as an exchanger it would give you a reasonable rise in the inflow temp.

Jon

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